1. Field of the Invention
The present invention relates to a composition with a continuous aqueous phase containing L-2-oxothiazolidine-4-carboxylic acid.
2. Background of the Invention
L-2-oxothiazolidine-4-carboxylic acid, or procysteine, is known as a component of cosmetic or dermatological compositions intended for topical application to the skin. Such compositions can be intended for preventing hair loss or for stimulating the regrowth of hair, as described in EP 656 201. Procysteine is also known from patent FR 2 742 658 as an agent for depigmenting or bleaching human skin.
However, procysteine has a certain level of instability, in particular when it is in the presence of water. Thus, when it is introduced into a cosmetic composition, in particular a composition comprising water, its efficacy decreases over time. In addition, after storage for a certain period, the composition into which it is introduced shows signs of degradation: coloration, odor, which users find unacceptable. One solution for stabilizing procysteine in water consists in combining it with a polyol, in specific amounts by weight, and in limiting the amount of water to a value of 35% by weight, and preferably less than 20% by weight, relative to the total weight of the composition.
Although these compositions do in effect make it possible to convey procysteine stably over time without any loss of efficacy of this active agent, not all users necessarily find their texture suitable and the need remains for compositions capable of containing large amounts of water, for example greater than 80% by weight, in particular in the form of oil-in-water emulsions.
Admittedly, compositions in the form of oil-in-water emulsions containing procysteine are known from EP 656 201, but the Applicant has observed that these compositions were not stable over time and led to a degradation of the procysteine, resulting in the development of a nauseating sulphureous odor and yellowing of the composition.